The present invention relates to a magnetic recording/reproducing apparatus for recording and reproducing both an audio signal and a video signal on and from a magnetic tape.
A HiFi-VTR (magnetic recording/reproducing apparatus) in the VHS system is known as an apparatus to record and reproduce two kinds of signals such as a video signal and an audio signal on and from the same magnetic tape. In such an apparatus a rotating drum has its circumferential surface at least a pair of rotating heads for recording and reproducing a video signal and a pair of rotating heads for recording and reproducing a HiFi audio signal so that in recording the HiFi audio signal-is first recorded on the entire magnetic layer of the magnetic tape to have a relatively great amplitude and the video signal is then recorded on the surface portion (upper portion) of the magnetic layer and on the audio signal so as to have a relatively small amplitude. As a result, the audio signal remains only at its deep portion (lower portion) of the magnetic tape so as to form two magnetic layers, thus simultaneously recording on the same magnetic tape two kinds of signals whose frequency bands are overlapped with each other. Recently, an attempt is being made to record a PCM audio signal (having a higher sound quality than a conventional FM audio signal) in accordance with the frequency division multiplex technique as disclosed in the Japanese Patent Provisional Publication No. 1-105301 where for accurately reproducing the audio signal an error correcting code is added with respect to the audio signal as will be described hereinafter. However, if a trouble such as instability of the rotational speed of the rotating drum occurs before the addition of the error correcting code, difficulty is encountered to effect suitable processes such as correction, interpolation and muting because of no detection of the error correcting code in reproduction. This causes occurrence of errors to generate abnormal sounds in reproduction.